/*
---------------------------------------------------------------------
   Terrain Renderer using texture splatting and geomipmapping
   Copyright (c) 2006 Jelmer Cnossen

   This software is provided 'as-is', without any express or implied
   warranty. In no event will the authors be held liable for any
   damages arising from the use of this software.

   Permission is granted to anyone to use this software for any
   purpose, including commercial applications, and to alter it and
   redistribute it freely, subject to the following restrictions:

   1. The origin of this software must not be misrepresented; you
      must not claim that you wrote the original software. If you use
      this software in a product, an acknowledgment in the product
      documentation would be appreciated but is not required.

   2. Altered source versions must be plainly marked as such, and
      must not be misrepresented as being the original software.

   3. This notice may not be removed or altered from any source
      distribution.

   Jelmer Cnossen
   j.cnossen at gmail dot com
---------------------------------------------------------------------
*/
#include "StdAfx.h"

#include "TerrainBase.h"
#include "TerrainVertexBuffer.h"
#include "TerrainNode.h"
#include "TerrainTexture.h"

#include "Rendering/Textures/Bitmap.h"

#include <cassert>

namespace terrain {
	using namespace std;

//-----------------------------------------------------------------------
// Heightmap class
//-----------------------------------------------------------------------

	Heightmap::Heightmap()
	{ 
		w=h=0;data=0; lowDetail=highDetail=0; normalData=0; squareSize=0.0f; 
	}
	Heightmap::~Heightmap()
	{ 
		delete[] data; 
		delete[] normalData; 
	}

	void Heightmap::Alloc (int W,int H)
	{
		w=W; h=H;
		data=new float[w*h];
	}

	void Heightmap::LodScaleDown (Heightmap* dst)
	{
		// reduce 33x33 to 17x17
		dst->Alloc ((w-1)/2+1,(h-1)/2+1);
		
		for (int y=0;y<dst->h;y++) {
			float *srcrow = &data[y*2*w];
			for (int x=0;x<dst->w;x++)
				dst->at (x,y) = srcrow [x*2];
		}
	}

	Heightmap* Heightmap::CreateLowDetailHM ()
	{
		lowDetail = new Heightmap;
		LodScaleDown (lowDetail);
		lowDetail->highDetail = this;
		return lowDetail;
	}

	void Heightmap::FindMinMax (int2 st, int2 size, float& minH, float& maxH)
	{
		//float minH,maxH;
		minH = maxH = at (st.x,st.y);
		for (int y=st.y;y<st.y+size.y;y++)
			for (int x=st.x;x<st.x+size.x;x++) {
				float v = at (x,y);
				if (minH > v) minH = v;
				if (maxH < v) maxH = v;
			}
	}

	// level > 0 returns a high detail HM
	// level < 0 returns a lower detail HM
	Heightmap *Heightmap::GetLevel (int level) 
	{
		Heightmap *hm = this;
		if (level > 0)
			while (hm->highDetail && level > 0) {
				hm = hm->highDetail;
				level --;
			}
		else
			while (hm->lowDetail && level < 0) {
				hm = hm->lowDetail;
				level ++;
			}
		return hm;
	}

	void Heightmap::GenerateNormals ()
	{
		normalData = new uchar [3 * w * h];

		uchar *cnorm = normalData;
		for (int y=0;y<h;y++)
			for (int x=0;x<w;x++) {
				Vector3 tangent, binormal;
				CalculateTangents(this, x,y,tangent,binormal);

				Vector3 normal = binormal.cross(tangent);
				normal.ANormalize ();

				*(cnorm++) = (uchar)((normal.x * 0.5f + 0.5f) * 255);
				*(cnorm++) = (uchar)((normal.y * 0.5f + 0.5f) * 255);
				*(cnorm++) = (uchar)((normal.z * 0.5f + 0.5f) * 255);
			}
	}


	void Heightmap::UpdateLower(int sx, int sy,int w,int h)
	{
		if(!lowDetail)
			return;

		for (int x=sx/2;x<(sx+w)/2;x++)
			for (int y=sy/2;y<(sy+h)/2;y++)
				lowDetail->at(x,y)=at(x*2,y*2);

		if (lowDetail)
			lowDetail->UpdateLower(sx/2,sy/2,w/2,h/2);
	}

//-----------------------------------------------------------------------
// Index calculater
//-----------------------------------------------------------------------

	IndexTable::IndexTable ()
	{
		for (int a=0;a<NUM_TABLES;a++)
			Calculate (a);
	}

#define TRI(a,b,c) {*(i++)=(a); *(i++)=b; *(i++)=c;}
#define VRT(x,y) ((y)*VERTC+(x))

	void IndexTable::Calculate (int sides)
	{
		IndexBuffer *buf = &buffers[sides];
		buf->Init (sizeof(index_t)*MAX_INDICES);
		index_t *begin = (index_t*)buf->LockData (), *i = begin;

		int ystart = 0, xstart = 0;
		int yend = QUAD_W, xend = QUAD_W;
		if (sides & left_bit) xstart++;
		if (sides & right_bit) xend--;
		if (sides & up_bit) ystart++;
		if (sides & down_bit) yend--;

		if (sides & up_bit) {
			for (int x=xstart;x<QUAD_W;x++) {
				if (x&1) {
					TRI(x-1, x+1, VERTC+x);
					if (x<xend) TRI(x+1, VERTC+x+1, VERTC+x);
				} else {
					TRI(x, VERTC+x+1, VERTC+x);
				}
			}
		}

		for (int y=ystart;y<QUAD_W;y++)
		{
			if (sides & left_bit) {
				if (y&1) {
					TRI(VRT(0,y-1),VRT(1,y),VRT(0,y+1));
					if (y<yend) TRI(VRT(1,y),VRT(1,y+1),VRT(0,y+1));
				} else {
					TRI(VRT(0,y),VRT(1,y),VRT(1,y+1));
				}
			}

			if (y>=ystart && y<yend) {
				for (int x=xstart;x<xend;x++)
				{
					TRI(y*VERTC+x, y*VERTC+x+1, (y+1)*VERTC+x+1);
					TRI(y*VERTC+x, (y+1)*VERTC+x+1, (y+1)*VERTC+x);
				}
			}

			if (sides & right_bit) {
				int x=QUAD_W-1;
				if (y&1) {
					TRI(VRT(x+1,y-1),VRT(x+1,y+1),VRT(x,y));
					if(y<yend) TRI(VRT(x,y),VRT(x+1,y+1),VRT(x,y+1));
				} else {
					TRI(VRT(x,y),VRT(x+1,y),VRT(x,y+1));
				}
			}
		}

		if (sides & down_bit) {
			int y=QUAD_W-1;
			for (int x=xstart;x<QUAD_W;x++) {
				if (x&1) {
					TRI(VRT(x,y),VRT(x+1,y+1),VRT(x-1,y+1));
					if (x<xend) TRI(VRT(x,y),VRT(x+1,y),VRT(x+1,y+1));
				} else {
					TRI(VRT(x,y),VRT(x+1,y),VRT(x,y+1));
				}
			}
		}

		size[sides]=i-begin;
		assert (size[sides]<=MAX_INDICES);
		buf->UnlockData ();
	}

#undef VRT
#undef TRI


	
	void SetTexGen (float scale)
	{
		float tgv[4] = { scale, scale, 0.0f, 0.0f };
		SetTexCoordGen(tgv);
	}

//-----------------------------------------------------------------------
// AlphaImage
//-----------------------------------------------------------------------
	AlphaImage::AlphaImage()
	{ w=h=0;data=0; lowDetail=highDetail=0; }
	AlphaImage::~AlphaImage()
	{ delete[] data; }

	void AlphaImage::Alloc (int W,int H)
	{
		w=W; h=H;
		data=new float[w*h];
		fill(data,data+w*h,0.0f);
	}

	bool AlphaImage::CopyFromBitmap (CBitmap& bm)
	{
		if (bm.type != CBitmap::BitmapTypeStandardAlpha)
			return false;

		Alloc (bm.xsize,bm.ysize);
		for (int y=0;y<h;y++)
			for(int x=0;x<w;x++)
				at(x,y)=bm.mem[w*y+x]*(1.0f/255.0f);

		return true;
	}

	AlphaImage* AlphaImage::CreateMipmap ()
	{
		if (w == 1 && h == 1)
			return 0;

		int nw = w/2;
		int nh = h/2;
		if (!nw) { nw = 1; }
		if (!nh) { nh = 1; }

		AlphaImage *mipmap = new AlphaImage;
		mipmap->Alloc (nw,nh);

		// Scale X&Y
		if (w > 1 && h > 1) {
			for (int y=0;y<nh;y++)
				for (int x=0;x<nw;x++)
					mipmap->at (x,y) = (at(x*2,y*2) + at(x*2+1,y*2) + at(x*2, y*2+1) + at(x*2+1,y*2+1)) * 0.25f;
		} else if (w == 1 && h > 1) { // Scale Y only
			for (int y=0;y<nh;y++)
				for (int x=0;x<nw;x++)
					mipmap->at (x,y) = (at(x,y*2) + at(x, y*2+1)) * 0.5f;
		} else { // if (w > 1 && h == 1) {
			for (int y=0;y<nh;y++)  // Scale X only
				for (int x=0;x<nw;x++)
					mipmap->at (x,y) = (at(x*2,y) + at(x*2+1, y)) * 0.5f;
		}
		return mipmap;
	}

	// NO CLIPPING!
	void AlphaImage::Blit (AlphaImage *dst, int srcx,int srcy,int dstx,int dsty,int w,int h)
	{
		for (int y=0;y<h;y++)
			for (int x=0;x<w;x++)
				dst->at (x+dstx,y+dsty) = at(x+srcx,y+srcy);
	}

	bool AlphaImage::Save (const char *fn)
	{
		SaveImage(fn, 1, GL_FLOAT, w,h, data);
		return true;
	}

	AlphaImage::AreaTestResult AlphaImage::TestArea (int xstart,int ystart,int xend,int yend,float epsilon)
	{
		bool allOne = true;
		bool allZero = true;

		for (int y=ystart;y<yend;y++)
			for (int x=xstart;x<xend;x++)
			{
				float v = at (x,y);
				if (v > epsilon) allZero=false;
				if (v < 1.0f - epsilon) allOne=false;
			}

		if (allOne) return AREA_ONE;
		if (allZero) return AREA_ZERO;
		return AREA_MIXED;
	}

	int TextureUsage::AddTextureCoordRead(int maxCoords, BaseTexture *texture)
	{
		if (texture->ShareTexCoordUnit())
		{
			for(size_t a=0;a<coordUnits.size();a++) {
				BaseTexture *t = coordUnits[a];
				if (t == texture)
					return (int)a;
				if (t->ShareTexCoordUnit() && t->tilesize.x == texture->tilesize.x && t->tilesize.y == texture->tilesize.y)
					return (int)a;
			}
		}
		else {
			for(size_t a=0;a<coordUnits.size();a++)
				if(coordUnits[a]==texture) return (int)a;
		}

		if (maxCoords >= 0 && maxCoords == (int)coordUnits.size())
			return -1;
		
		coordUnits.push_back (texture);
		return (int)coordUnits.size()-1;
	}

	int TextureUsage::AddTextureRead (int maxUnits, BaseTexture *texture)
	{
		if (maxUnits >= 0 && maxUnits == (int)texUnits.size())
			return -1;

		for(size_t a=0;a<texUnits.size();a++)
			if(texUnits[a] == texture) return (int)a;
		texUnits.push_back(texture);
		return (int)texUnits.size()-1;
	}
};
